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  1. Sorry - I missed the “any”... Besides checking the cable and the connector, I’m not much of a help further into the logicbard I hope someone more knowledgeable steps in and you’ll work it out!
  2. Hi! It’s probably a stuck keyswitch on the keyboard that needs a cleaning? Some electronic cleaner might do the trick, but if that isn’t enough you might have to try disensamble the keyswitch and clean the inside. I haven’t tried this on a Plus keyboard but there might be instructions somewhere on the net. There’s also a couple of caps inside the keyboard that might need to be replaced. @JDW has a nice video on the subject - I don’t remember if there’s instructions for cleaning in this video.
  3. You can try both motherboards to rule out faults on the original motherboard. As fare as I know the 550 also should work without further modifications on hardware or in software. Edit: The 575 would probably boot, but not give any video on the screen without hacking the system software?
  4. I recaped my Colour Classic analogboard and found the PL2 pot (VG2) had to be reduced to let the machine boot. My guess was that the recap changed the voltage to healthy levels and my old previous setting was to high for the powersupply? PL2 = G2 in the service manual. Somebody who`s into electronics and how the analogcircuit works might have an answer.
  5. I saw JDWs excellent video on recapping the SC20 HD (https://www.youtube.com/watch?v=Qof-Wjj_rWI&feature=youtu.be). Here he demonstrated that one off the new caps actually is to “good” (low ESR), making the transformer next to it make a comparable noise at startup. Could that be something? Edit: I’m not too into electronics and wouldn’t know what and where to measure the inductor coils
  6. Hi, @Franklinstein! Sorry for resurrecting an old thread. Did you figure this out? I have a 6500 mb that have the same problem after recap. It does restart from the keyboard, but wont boot. The HD boots fine with a 5400 mb in the same machine. I haven’t tried with a p-ram battery though.
  7. Hi! The machine shutting down probably was because G2 (voltage?) on the analog board was sett to high after recap. But The 300mhz MB still won`t boot. There`s a nice chime, the HD-spins but doesn`t look for a system folder and the screen stays black. I can reboot the computer from the keyboard. I also tried to boot without RAM and cache - same result As said the 5400 MB still boots fine. I`ve changed all the pots in the Video section (Sub-contrast, Green-drive, Blue-drive, Red background, Green background and Blue background). First boot the blue channel was fine, but the gre
  8. Update: changed both pots for Blue Gain and Blue Background. The blue channel was back for a while and then disappeared again. Am I right assuming the videosignal comes from the analogboard edge connector, through the gray cabel into the white connector to the left in the picture in my last post and out to the CRT-board through the white connector to the left? Ps. Also recapped my 6500- 300mhz motherboard. Forgot to connect the CPU-fan. Boot chime, HD-spinn, no screen and then the machine shut down. Could I have burned the CPU in that short time? My 5400-160mhz MB still works
  9. Yes, it might be. I was wondering if the low voltage from my powerbrick is making these coils struggle at startup? Mine are looking a little better than yours and have a different number on them. But Google won’t help me find our what they are.
  10. I think Phier is the brand name on the trim-pot
  11. Its not dead! Washed the board with isopropyl alcohol and a toothbrush and rinsed in tap-water (I know this is wrong) and let it dry a couple of days. It booted when put in the powerplug. A shriek from the corner of the MB with caps before booted fine and reached the desktop. The unpolarised ceramic caps in the screen seem to be working fine. But I`m a little disappointed that the screen still has pronounced ghosting and lines. Turns out the contrast knobs on the screen doesn`t do anything (I guess they didn`t before my tinkering either). And my recapped pow
  12. Changed this cap one more time, and the image is stabel again! Still waiting for new pots to see if that fix the blue channel.
  13. Yes, your right! The diameter is to small. Here is pictures of my board with new caps.
  14. Yes, that’s correct. There’s four leads to the plug and four terminals.
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